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Test for Mass Spectroscopy activity
Name_________________________ Date___________________________
Teacher _______________________ Class __________________________
1. The ability of a mass spectrometer to separate particles by mass is based on the
principle that:
a. the motion of charged particles can be affected by a magnetic field;
b. the motion of charged particles can be affected by a gravitational field;
c. the motion of charged particles can be affected by an electric field.
Selects A.
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2. While running a mass spectrometer, the following mass spectrum of a gaseous
compound is produced.
(graph adapted from: http://www.cem.msu.edu/~reusch/VirtualText4/Questions/Spectroscopy/masspec3.htm)
Relative
Intensity
Mass
The "relative intensity" is related to the number of ions arriving at the mass
spectrometer’s detector: the more abundant the ion, the greater the relative intensity.
2a. What is the mass of the most common ion?
Records 28.
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2b. What are masses of the other ions?
Response includes…
Response includes 15; 26; 30
Response includes some of the above but not all
Other
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3. The detector in a mass spectrometer would NOT measure the mass-to-charge ratios of
substances that:
a. are positively charged
b. are ions
c. have no charge
Selects C
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4.The picture below shows a charged particle moving through a chamber in a mass
spectrometer. As the particle enters the magnetic field, the field causes the particle to
move in a curved path as shown by the black line. The path currently shows a particle
curving below the red sensor [the filled in box] on the left side of the chamber.
4a. Would a technician need to increase or decrease the strength of the magnetic field in
the mass spectrometer to get the particle in the picture to hit the sensor.
Response includes…
Technician would need to decrease the strength of the
magnetic field.
Other
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4b. If particles with half of the mass of the particle shown in the illustration above were
placed in the mass spectrometer but all other settings were equal, predict approximately
where the particle would hit the wall. Explain your prediction.
Response includes…
The particle would hit the bottom wall. The magnetic
force would pull the lighter massed particle down
because the force would be stronger on the particle.
Particle hits bottom wall -- but doesn’t give a reason.
Other
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2
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